1. Field of the Invention
The present invention relates to a musical performance device, a musical performance method, and a storage medium for performing automatic accompaniment by synchronizing accompaniment sound obtained by audio replay with musical sound generated in response to a musical performance operation.
2. Description of the Related Art
A device has been known which performs automatic accompaniment by synchronizing accompaniment sound obtained by audio replay with musical sound generated in response to a musical performance operation. As this type of device, a technology is disclosed in Japanese Patent Application Laid-Open (Kokai) Publication No. 2012-220593 in which a lesson function is provided for guiding a user to a key to be played next based on musical performance data and waiting until the guided key is pressed, and the audio replay of accompaniment sound (audio waveform data) is performed in synchronization with musical sound generated in response to the press of the key guided by this lesson function.
In the technology disclosed in Japanese Patent Application Laid-Open (Kokai) Publication No. 2012-220593, the progression of a musical piece (read of musical performance data) is stopped until a guided key is pressed. Here, if accompaniment sound obtained by audio replay is also stopped, the sound is interrupted, which causes unnaturalness. Therefore, until the guided key is pressed, the accompaniment sound (audio waveform data) which is being emitted in synchronization with the previous key press is loop-replayed and continuously emitted as accompaniment sound during standby.
Specifically, a search is made for a loop start point (zero-cross point in the same phase) of accompaniment sound (audio waveform data) corresponding to the pitch of the guided key, and the accompaniment sound (audio waveform data) from the corresponding loop start point (loop address) to an end address is repeatedly replayed. As a result of this configuration, the audio replay of accompaniment sound with a natural musical interval can be performed even during standby for key press.
However, in a case where the accompaniment sound (audio waveform data) is rhythmical, not only changes in the musical interval but also changes (attenuation) in the waveform amplitude are large. Therefore, when the accompaniment sound is loop-replayed, beats in that period become conspicuous. That is, there is a problem in that the audio replay of accompaniment sound with a natural beat cannot be performed during standby for key press.